Re: Cracks in Paraffin Wax Blocks

From:

Sharron Ladd

Are you using metal molds? I learned in a NSH workshop, that leaving the
blocks chilling too long on the cold plate (in metal molds) can cause
cracks to form in the paraffin.
Sharron
ncragg wrote:
>Dear All,
>
>Please could anybody tell me why I am getting cracks in my paraffin wax
>blocks? I noticed someone had asked this question a couple of years ago
>but there was no reply posted. I can still cut sections from these blocks
>and they look fine under the microscope. Not all the blocks in a batch are
>cracked, some are nice and I've even had batches where 90% of the blocks
>are good and only a few have cracks.
>
>We use Surgipath Formula R paraffin wax and I have spoken to the rep there
>and he suggested a couple of things, but none have made any difference; he
>has also checked the batch of wax we were using and there are no reported
>problems; besides we are now onto another batch and the same thing happens.
> I have wondered whether it is my embedding technique, but have tried many
>different ways, e.g. different amounts of wax in the base mould before
>orientation, different lengths of time on the refrigeration spot before
>topping up and different methods of cooling, ie. using the coldplate and
>-20 freezer. I am also careful not to move the tissue once the wax starts
>to solidify. The wax is melted at 60 degrees celsius in the processor and
>the embedding centre is also set at 60.
>
>I would be very grateful if anyone has anyone got any suggestions?
>
>Thanking you in advance.
>
>Nicola Cragg
>Epistem Ltd.
>Manchester, UK
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